Durability is a key requirement for modern infrastructure projects – highways and roads, bridges, airports and airfields, walkways and plazas, parking structures and stadiums. Miles of concrete must be designed to accommodate significant movement – especially in the joints – caused by unrelenting weather, temperature extremes, UV radiation and chemicals, such as de-icing materials and fuels.
Dow offers a broad portfolio of technologies and expertise to support infrastructure projects. The company is developing innovative products, while following sustainable practices, and using proven, durable materials. Dow sealants, for example, provide excellent durability, long-term adhesion, elastic recovery and elongation – without cracking over time. These silicones offer exceptional performance under long-term UV exposure and high temperatures.
DOWSIL™ Sealant Technologies
There are many different technologies used in infrastructure sealing applications – especially for joints exposed to high temperatures and UV, where long-term durability is necessary. Some of the demanding requirements for sealants in highways, airports and other infrastructure applications include:
- Watertight and long-lasting joints
- Accommodating extreme movements
- No cracking
- Excellent weatherability
- Fast and easy installation
- Long service life.
DOWSIL™ pavement joint sealants are cold applied without the need for heating or other special preparation. Suitable for application over a wide temperature range, they cure using moisture in the air, and the skin-over time is one hour or less – allowing roadways to be opened to traffic quickly.
Dow silicone sealants are flexible; this is because every DOWSIL™ pavement silicone joint sealant has a movement capability of 100% expansion and 50% compression, once cured. The silicones resist hardening in cold temperatures and softening in warm weather, and due to their weatherability they are unaffected by rain, snow, sunlight, ozone or temperature extremes.
Features of DOWSIL™ 888 Silicone Joint Sealant
DOWSIL™ 888 Silicone Joint Sealant can be used with a primer for concrete-to-steel and steel-to-steel joints, and can seal joints that are not uniform in width or have minor spalling. It is weather and UV resistant, as well as fuel resistant for short-term exposure. It can accommodate extreme movement – 100% extension and 50% compression
This low-modulus sealant is ready to use as supplied and is dispensed directly from the bulk container into the joint – by hand or with an air-powered pump. It can be extruded from -30 to 50°C. Recommended maximum joint width for typical applications as airport runway or taxiways is two inches (5.08 cm).
However, it should not be used with asphalt as the product’s modulus might be high enough to induce additional stress, which could lead to asphalt substrate spall when subject to joint movement.
Features of DOWSIL™ 890-SL Silicone Joint Sealant
This self-levelling, one-part sealant can be used for concrete-to-concrete and concrete-to-asphalt pavement joints without a primer. With a primer, it also can be used for concrete-to-steel and steel-to-steel joints. It will flow into irregularly shaped and spalled joints with no tooling required.
This ultra-low-modulus sealant is ready to use as supplied. An ultra-low modulus is important for asphaltic paving to help ensure minimal stress is placed on the joint face. It can be extruded from -30 to 50°C. The cured silicone rubber remains flexible from -30 to 150°C. It can accommodate extreme movement – 100% extension and 50% compression. It is weather and UV resistant, as well as fuel resistant for short-term exposure. Recommended maximum joint width for typical applications is two inches (5.08 cm).
Features of DOWSIL™ 902 RCS Joint Sealant
This rapid-cure, self-levelling, two-part sealant can be used for concrete-to-concrete, concrete-to-asphalt, concrete-to-steel, and steel-to-steel expansion joints. The typical applications are bridge or highway expansion joints that vary in width from 25 to 76 mm.
This sealant’s rapid cure makes it especially well-suited for maintenance work where resealing must be completed within a short period of time to minimize traffic disruption. Its rapid cure develops sufficient integrity within eight hours to accommodate movements associated with bridges. With all-temperature gunnability, this ultra-low modulus, self-levelling sealant will seal irregularly shaped and spalled joints with no tooling required. Under normal conditions, this sealant remains rubbery from -45 to 150°C without cracking, tearing, or becoming brittle.
The two-part formulation offers the ease of a one-part installation – with no premixing or measuring required. The product is available in convenient EZ Pak sausages, making it easy to load, use, dispose and minimize material waste. The two EZ Pak sausages (592 mL each) are easily dispensed in a 1:1 ratio with a dual-sausage pneumatic gun. The sealant components are also available in larger bulk pails.